Hello everyone, congratulations on the APP!
It is already very useful, but below is a suggestion for improvement.

The App could allow the use of URLs for predefined texts.
This would be very helpful for people who want the fields to be loaded with predictable texts.

And also reuse links

Ex:
1 - https://mailtolink.me/?to=xpto@acme.com?sub=SubjectText?Body=BodyText
In the first example, the site already loads with the fields filled in, and the user only needs to update the text before generating the MailTO

2- https://mailtolink.me/?to=xpto@acme.com?sub=SubjectText?
In the second example, the site only loads the email recipient and the subject, and the user only needs to type the body of the message.